Some industrial, commercial, medical, aerospace and military systems depend on reliable pressure sensors for fluid (including gas) handling. Pressure transducers that use piezoresistors may be formed with a silicon substrate and an epitaxial layer, which is grown on the substrate. A portion of the substrate is removed, leaving a thin, flexible diaphragm. The piezoresistors are located in the diaphragm to form a pressure transducer.
In operation, at least one surface of the diaphragm is exposed to a process pressure. The diaphragm deflects according to the magnitude of the pressure, and this deflection bends the attached piezoresistors. Bending of the diaphragm may create a change in the resistance value of the piezoresistors. The change in the resistive value may be reflected as a change in the output voltage signal of a resistive bridge formed at least partially by the piezoresistors. The silicon-based sensors and actuators may have limitation in versatility and may be relatively costly.
In the figures, like reference characters designate identical or corresponding components and units throughout the several views.